Drill/driver hybrid instrument for interphalangeal fusion

ABSTRACT

Surgical techniques, instruments and systems for bone fusions and repairs (for example, phalangeal fusion) which allow alignment of small bones (for example, phalanges) without the use of guidewire and cannulated instrumentation such as, for example, drills and drivers, and cannulated screws. A drill/driver hybrid instrument (a combined drill/driver device) may be used in fusion of two small bones (for example, in interphalangeal fusion). One end of the hybrid instrument is provided with a plurality of flutes so that the instrument can be used as a drill to remove bone. The other end is shaped to mate with a device to be inserted intraarticularly (for example, interphalangeally), acting as a driver for that device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/206,885, filed Mar. 12, 2014, which claims the benefit of U.S.Provisional Application No. 61/778,513, filed Mar. 13, 2013, thedisclosures of which are incorporated by reference in their entiretyherein.

FIELD OF THE INVENTION

The present invention relates to the field of surgery and, moreparticularly, to improved instruments, systems and methods for smalljoint repairs (hand, wrist and foot repairs, for example) and ligamentreconstructions.

BACKGROUND OF THE INVENTION

Phalanges of the hand are known as finger bones. Phalanges of the footare known as toe bones. The metacarpals are tiny long bones in the handthat connect the phalanges to the carpals. The metatarsals are shortbones in the foot that connects the phalanges to the tarsals.

Interphalangeal joints are the joints between the phalanges. These smalljoints are typically classified as “proximal interphalangeal joints”(PIP or PIPJ, or joints between the first (proximal) and second(intermediate) phalanges) or “distal interphalangeal joints” (DIP orDIPJ, or joints between the second and third (distal) phalanges).

Abnormalities associated with disruptions of these small joints (such asPIP or DIP joints) are caused by biomechanical abnormalities (forexample, where certain tendons, ligaments, and supportive structures ofthe joint are no longer functioning correctly) or other various injuries(for example, sport injuries).

The PIP joint is a hinge joint that is normally kept in alignment by asoft tissue envelope consisting of joint capsule, the volar plate,collateral ligaments and the central slip. These structures form atight-fitting “box” with a very narrow joint space. When injuries tothis soft tissue envelope occur, they can be either partial or completeand they cause disruption to the collateral ligaments and adjacentstructures.

Similarly, when the first metatarsophalangeal joint (MTP) (which is oneof the joints in the big toe) is affected by arthritis, for example(such as Hallux Rigidus), the cartilage of the joint becomes damagedwhich in turn can cause extreme pain and stiffness. To alleviate pain, afusion operation (arthrodesis) is recommended to totally remove thedamaged cartilage and to fuse the two bones that form the joint. Thefusion is usually secured by either two fixation devices (for example,screws) or a plate that remain in toe permanently.

There is a need for a small joint repair technique that is simple and isperformed by a minimally invasive “all-inside” approach. Also needed isa novel instrument that allows both removal of bone from a small bone(for example, phalanx) and also insertion of a fixation device (forexample, implant) into the bone.

SUMMARY OF THE INVENTION

The present invention provides surgical techniques, instruments andsystems for bone fusions and repairs (for example, phalangeal fusion)which allow alignment of small bones (for example, phalanges) withoutthe use of guidewire and cannulated instrumentation such as, forexample, drills and drivers, and cannulated screws.

The present invention provides a drill/driver hybrid instrument (acombined drill/driver pin) that may be used in fusion of two small bones(for example, in interphalangeal fusion). One end of the hybridinstrument is provided with a plurality of flutes or threads so that theinstrument can be used as a drill to remove bone. The other end isshaped to mate with a device to be inserted intraarticularly (forexample, interphalangeally), acting as a driver for that device.

The present invention also provides fusion methods for small bones by aminimally invasive all-inside approach. The method comprises the stepsof: (i) providing a single-shaft drill/driver hybrid instrument in thevicinity of a small bone joint; (ii) forming a bone tunnel/socket withone end of the hybrid instrument; and (iii) engaging/inserting a device(for example, a fixation device such as screw repair implant) with theanother end of the instrument.

These and other features and advantages of the present invention willbecome apparent from the following description of the invention that isprovided in connection with the accompanying drawings and illustratedembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a front view of a drill/driver hybrid instrumentaccording to an exemplary embodiment of the present invention.

FIG. 1(a) illustrates a cross-sectional view of the drill/driver hybridinstrument of FIG. 1, taken along line A-A of FIG. 1.

FIG. 1(b) illustrates another front view of the drill/driver hybridinstrument of FIG. 1.

FIG. 1(c) illustrates a left-side view of the drill/driver hybridinstrument of FIG. 1.

FIG. 2 illustrates a front view of a drill/driver hybrid instrumentaccording to another exemplary embodiment of the present invention.

FIG. 2(a) illustrates a cross-sectional view of the drill/driver hybridinstrument of FIG. 2, taken along line A-A of FIG. 2.

FIGS. 3-6 illustrate subsequent steps of an exemplary method ofphalangeal fusion with the drill/driver hybrid instrument of FIG. 1.

FIG. 7 illustrates a front view of an internal fixation device (a solidrigid screw) according to an exemplary embodiment of the presentinvention.

FIG. 7(a) illustrates a right-side view of the internal fixation deviceof FIG. 7.

FIG. 7(b) illustrates a left-side view of the internal fixation deviceof FIG. 7.

FIG. 7(c) illustrates another view of the internal fixation device ofFIG. 7 rotated about 90 degrees.

FIG. 7(d) illustrates a cross-sectional view of the internal fixationdevice of FIG. 7 taken along line A-A of FIG. 7.

FIG. 8 illustrates an X-ray of the foot showing the head of the internalfixation device of FIG. 7 fully seated in the middle phalanx.

FIGS. 9-13 illustrate subsequent steps of an exemplary method ofphalangeal fusion with the internal fixation device of FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides methods and apparatus for small bonerepairs and fusion, with particular application to phalangeal repairsand fusions.

The present invention provides surgical procedures, instruments andsystems for bone fusion and repair (for example, phalangeal fusion)which allow alignment of small bones (for example, phalanges) withoutthe use of guidewire and cannulated instrumentation, e.g., screws.

An exemplary instrument of the present invention is a drill/driverhybrid instrument (a combined device) in the form of a solid rigid pinthat may be used in small bone repairs, for example, interphalangealfusion. The hybrid instrument is provided with first and second ends.One of the first and second ends (the “drill” end) has a plurality offlutes/threads so that the instrument can be used as a drill to removematerial from bone (phalangeal canals). The other of the first andsecond ends (the opposite end or the “driver” end) is shaped toengage/mate with a device to be inserted intraarticularly (e.g.,interphalangeally) and acts as a driver for that device. The “driver”end could have any suitable cross-section, for example, hexagonal,hexalobe, cruciform, a “star” like configuration, or any other shape andgeometry that allows the end to mate with an implanted device in thejoint.

Another exemplary device of the present invention (which could be usedwith the methods of fusion and small bone repairs) is a fixation devicein the form of a small screw with two separate threads on a shaft. Theshaft may be selected to have a diameter corresponding to the size ofthe bones to be fused/repaired. In an exemplary embodiment, the diameterof the shaft may be of about 1.5 mm to about 4.5 mm, preferably about 2mm or less. For metatarsals or other bones, however, the diameter may belarger than 2 mm. The threads have different directions and are providedat a proximal end and at a distal end, respectively, of the shaft of thefixation device. The threads are opposing so that, during insertion, thesmall screw can be turned clockwise to allow for simultaneous andopposite engagement of both phalanges (bone fragments). This allows forappropriate placement of the screw and toe prior to compression.

Referring now to the drawings, where like elements are designated bylike reference numerals, FIGS. 1-6 illustrate exemplary embodiments ofdrill/driver hybrid instrument/pin 100, 100 a of the present inventionand methods of bone fusion and repair employing such instrument/pin 100,100 a. FIGS. 7-13 illustrate exemplary embodiments of a solid fixationdevice 195 (an exemplary retro compression solid screw) and exemplarymethods of implanting the solid fixation device according to the presentinvention.

In the embodiments below, instrument/pin 100, 100 a and fixation device195 are described with reference to a particular interphalangeal repair(fusion) in the foot. The invention is not limited, however, to thisspecific exemplary embodiment and encompasses hybrid instruments andaccompanying fixation devices with application to any other small jointrepairs and any other interosseous ligament reconstructions, forexample, MTP and MCP joint repairs, syndesmotic injuries and halluxvalgus repairs, among many others. Thus, the instruments and methods ofthe present invention have applicability to the repair and/or fusion ofany adjacent bones, for example, adjacent phalanges, metatarsals,metacarpals, tarsals or carpal bones.

Hybrid instrument 100, 100 a of FIGS. 1-2(a) is provided with a firstend 20 (drill end 20) and a second end 40 (opposite end 40 or driver end40). In an exemplary embodiment, first end 20 of pin 100 (FIG. 1) isprovided with a sharp tip 21 and a plurality of threads 22 configured toremove bone (drill) and form a bone socket/tunnel, as detailed below. Inanother exemplary embodiment, first end 20 of pin 100 a (FIG. 2) isprovided with a sharp tip 21 and a plurality of drilling flutes 22 aconfigured to remove bone (drill) and form a bone socket/tunnel, asdetailed below.

Second end 40 is provided with an end geometry 44 configured to engage(mate with) a device (for example, a fixation device such as a screw) tobe inserted intraarticularly (for example, interphalangeally). Thesecond end 40 acts as a driver for that device (fixation device). Thesecond end 40 (driver end 40) could have any suitable cross-section, forexample, hexagonal, hexalobe, cruciform, a “star” like configuration, orany other shape and geometry that allows the end to mate with a deviceto be implanted into the joint (for example, interphalangeal joint).FIGS. 1(c) and 2(a) show the second end 40 having an exemplary hexagonalcross-section.

Drill/driver instrument 100, 100 a is designed to be used both fordrilling bone and for engaging a fixation device to be inserted into thebone by an “all-inside,” minimally invasive approach and with minimaltrauma to the patient. The instrument/pin 100, 100 a may be providedwith markings to aid in assessing the drill and/or insertion depth. Thediameter of instrument/pin 100, 100 a may be about 1.0 mm to about 4.5mm, more preferably about 1.5 mm to about 2.0 mm.

FIGS. 3-6 illustrate an exemplary method of interphalangeal joint repair(phalangeal fusion) with exemplary instrument 100 of FIG. 1.

FIG. 3: Hybrid instrument/pin 100 of the present invention is used todrill into proximal phalanx 80 of interphalangeal joint 90 with firstend 20 (drill end) of the instrument. Metatarsal 70 is illustrated aspart of toe 60. To facilitate drilling of the instrument 100 intophalanx 80 to form phalangeal canal 88 (bone tunnel or socket 88), ahandle 50 may be securely attached to end 40 of the instrument.Phalangeal canal 88 of proximal phalanx 80 is formed by drillthreads/flutes 22 (which may be hand drilled or operated under power).Handle 50 attaches to the driver end 40 to allow the application oftorque to the drill threads/flutes 22.

FIG. 4: The drill end 20 of hybrid instrument/pin 100 is removed fromthe proximal phalanx 80 and then used in middle and distal phalanges 81,82 to create a tunnel 88 a through the tip of the toe 60 (i.e., drillingin the direction of arrow A, from a first surface 81′ of distal phalanx81 to a second surface 81″ of the distal phalanx 81). This procedurecould be also done with the drill coming out before the end of the toe,i.e., out of the dorsal aspect, just proximal to the DIPJ. This wouldallow for a flexed fusion which is preferred by some surgeons.

Also shown in FIG. 4 is internal fixation device 195 (implant 195 orretro compression screw 195) that will mate later with end 40 of thehybrid instrument/pin 100 (through a socket or opening provided at thedistal end of fixation device 195 and configured to engage and mate withthe end 40, as detailed below). Implant 195 is shown partially insertedwithin bone tunnel or socket 88; however, implant 195 may be alsoprovided fully inserted in bone tunnel or socket 88 (i.e., first set ofthreads 166 may be partially or fully inserted/threaded within bonetunnel or socket 88). Details of implant 195 are illustrated in FIGS.7-7(d). Depending on the particular application, the outer diameter ofthe fixation device 195 is slightly larger than the diameter of therespective bone tunnel or socket to be threaded therein, to allow thethreads of the shaft of the fixation device 195 to adhere to theinternal walls of the bone tunnel or socket.

FIG. 5: The handle 50 can then be removed from the interphalangeal area90 and reattached outside of the toe 60 (i.e., attached to the first end20). The driver end 40 remains within the phalanx 81 near surface 81′ toengage fixation device 195 (implant 195) and drive this device into bonetunnel 88 of proximal phalanx 80 and also into bone tunnel 81 a ofmiddle phalanx 81. As the handle 50 is rotated in a clockwise directionB, the fixation device 195 is advanced in a first direction (forexample, in a forward direction) in bone 80 as threads 166 advancewithin the bone tunnel 88, and also in a second direction which isopposite the first direction (for example, in a backwards direction) inbone 81 as threads 177 advance within the bone tunnel 88 a. The fusionof the bones 80, 81 is a result of the opposing threads 166, 177 of thefixation device 195, as detailed below. In this manner, one end of therigid fixation device 195 is threaded within a first bone tunnel (i.e.,bone tunnel 88) and the other end of the rigid fixation device 195 isthreaded within a second bone tunnel (i.e., bone tunnel 88 a) to alignthe two bone tunnels 88, 88 a and the two bones 80, 81. If the fixationdevice 195 is fully seated (fully threaded) within the bone tunnel orsocket 88, then rotation of the handle 50 in the direction of arrow Ballows threading of the fixation device 195 only in the bone tunnel orsocket 88 a to allow the two bones 80, 81 to be brought together andfuse.

FIG. 6: The device 100 can then be removed from the distal end of thetoe 60 and the implant 195 of repair 99 is left in the joint 90 (forexample, interphalangeal joint 90).

The drill/driver hybrid device/pin 100, 100 a of the present inventioncould be used for implantation in the proximal interphalangeal joint(PIP) or distal interphalangeal joint (DIP) of the hands and/or feet.Device 100, 100 a could also be used at the metatarsal-phalangeal (MTP)or metacarpal-phalangeal (MCP) joints.

Device/pin 100, 100 a could benefit an “all-inside” implant thatfuses/reconstructs/repairs/spans the joint and is inserted from withinthe joint. The device/pin 100, 100 a is used for drilling bone and alsoengaging an implant (fixation device such as a screw, for example).

The reconstruction system and procedure detailed above offer a minimallyinvasive approach. The single-shaft hybrid instrument 100, 100 a withdrill end 20 and driver end 40 allows both the formation of a bonetunnel (phalangeal tunnel) and also the insertion of a screw repairimplant, with minimal trauma to the patient.

FIGS. 7-7(d) illustrate another exemplary embodiment of fixation device195 (retro compression screw 195) of the present invention. Fixationdevice 195 is preferably solid (non-cannulated) and rigid to allowimplantation into bone without the need for cannulated fixation devicesand associated instrumentation.

Fixation device 195 is an exemplary small screw with two separatedthreads 166, 177 provided on a shaft 110 which may have any diametercorresponding to the particular bone application, for example, about 4.5mm or less, preferably 2.0 mm or less, depending on the bones to befused and/or the particular application (i.e., larger bones wouldrequire larger diameter screws). Proximal threads 166 are provided at aproximal end 112 of the shaft 110. Distal threads 177 are provided at adistal end 114 of the shaft 110. The proximal and distal threads 166,177 have opposite threads to allow for compression of the two bones withclockwise revolutions. Fixation device 195 may have any length dependingon the particular bone application/repair. In an exemplary onlyembodiment, the screw 195 could be from about 12 mm to about 40 mm inlength, preferably about 20 mm to about 40 mm in length. The threadswithin the proximal phalanx are long and the threads within the middlephalanx can be wider (i.e., similar to a Herbert screw). Distal end 114is also provided with a socket or opening 144 that is configured toengage and mate with the end 40 of hybrid instrument 100, and asdetailed below.

The novelty of the device 195 consists in the opposing threads 166, 177on the shaft and in the insertion technique. The threads 166, 177 areopposing so that, during insertion, the screw can be turned clockwise toallow for simultaneous and opposite engagement of both phalanges. Thisallows for appropriate placement of the screw 195 and toe prior tocompression.

Exemplary internal fixation device 195 of FIG. 7 may be also employedfor fixation of hammertoes during reconstruction, or for otherfixations/repairs. Fixation device 195 is rigid, provides compressionand is easily implanted, similar to the standard technique of pinfixation, as shown with reference to FIGS. 8-13.

Hammertoe surgery is a very common procedure which is typicallyperformed with resection of the proximal interphalangeal joint (PIP orPIPJ). The most common known fixation technique utilizes a smooth k-wirethat is later removed. A bioabsorbable pin may be also employed, butthis pin is typically too weak and does not provide compression. Inaddition, when fusion of the joint is required, unfavorable results mayoccur, generally related to deformity and delayed union causingprolonged swelling.

Internal fixation is also accompanied by problems. The device must beplaced into the PIPJ without damage to the DIPJ. During the resection ofthe joint, only the PIP is exposed. The bones are quite small,especially the middle phalanx 81 which has a length between 5 mm to 20mm. The diameter of the proximal phalanx 80 is also small and averagesapproximately 2 mm. Longitudinal alignment during insertion of thedevice is difficult to maintain.

Fixation device 195 of the present invention overcomes the aboveproblems. By being provided with two separate and different threads on asmall shaft, fixation device 195 can be turned clockwise to allow forsimultaneous and opposite engagement of both phalanges (due to theopposing threads). This allows for appropriate placement of the screwand toe prior to compression.

The insertion technique with fixation device 195 is designed to mimictypical articular joint (for example, PIPJ) fixation with a smooth pin.First, a smooth pin of about 1.5 to 2.0 mm diameter is driven prograde(antegrade) or distally out the end of the toe (similarly to thestandard technique). This pin has one sharp end and the other end has asmall hexagonal shaped tip that fits into the screw. The pin is alsomarked for measurement purposes. An exemplary pin is instrument 100, 100a of FIGS. 1 and 2.

Once the pin position is acceptable, the screw 195 is started retrogradeinto the proximal phalanx 80. When it is inserted to within a fewmillimeters of the distal threads 177, it is placed onto the hex driverend 44 of the pin 100 in the distal part of the toe 60. Then, as the pin100 is turned clockwise using the pin protruding out the tip of the toe,the two bone fragments 80, 81 are drawn together. The pin is thenremoved from the toe leaving only the screw 195 across the articularjoint, for example, DIPJ or PIPJ joint.

The desirable lengths and the markings on the insertion pin 100 requiredfor sizing the pin may be calculated appropriately. Another benefit ofthe design of fixation device 195 is that the threads engaging themiddle phalanx can be large without damaging the DIPJ. The only specialtools that are required beyond a wire driver are a small screwdriver anda hand-held chuck to rotate the pin 100.

FIG. 8 illustrates an X-ray of the foot showing the head of the internalfixation device 195 of FIG. 7 fully seated in the middle phalanx 81 oftoe 60 as part of fusion repair 199.

FIGS. 9-13 illustrate subsequent steps of an exemplary method ofphalangeal repair with the internal fixation device 195 of FIG. 7.

FIG. 9: Step 1—Retrograde cannulation of proximal phalanx 80 adjacentmetatarsal 70 with hybrid instrument/pin 100; make note of length “A.”FIG. 9 also shows the resected ends of the proximal and distalphalanges.

FIG. 10: Step 2—Cannulate toe tip; same pin (for example, instrument100) is driven prograde out of toe tip; two measurements are taken; “B”represents the depth until PIPJ is fixed; pin 100 is inserted when DIPJhas crepitus; take measurement—this is the length of the middle phalanx81.

FIG. 11: The pin 100 is driven to just under the skin at the toe tip;take third measurement “C.” This provides final insertion length “D”(C-B=D);

Step 3—Pin 100 driven until flush with middle phalanx 81.

FIG. 12: step 4—Screw 195 inserted retrograde into proximal phalanx 80with a small insertion driver 190; screw 195 is inserted until few mm ofthe shaft are still visible; only the hex drive 44 of the pin 100 isvisible (insertion pin 100 remains in place).

Step 5—Straighten the toe and engage hex end 44 of pin 100 in socket 144of screw 195; this may be difficult as there is limited space in thedissection between the bones (typically 10-15 mm distraction ispossible).

FIG. 13: Step 6—rotate the insertion pin 100 (with screwdriver 180) in aclockwise manner to compress the bones 80, 81; as the pin 100 is turned,care should be taken to ensure that the threads in the middle phalanxengage; as the bones 80, 81 compress and the threads work into theproximal phalanx, complete insertion is monitored by 1) visualizing thebone and 2) observing the measurement on the pin 100 (should be equal toor just less than “D” from above).

Implant (fixation device) 195 described above may be an exemplaryhammertoe screw employed, for example, in a metatarsal osteotomy forbunionectomy. Implant 195 may be part of a kit (set) for metatarsalosteotomy, or may be provided separately, in various lengths and/ordiameters. As noted, implant 195 is solid to allow implantation/fixationinto bone without the need for cannulated implants and instruments. Inparticular applications, however, the invention also contemplates afixation device that is partially cannulated (or even fully cannulated).

While the present invention is described herein with reference toillustrative embodiments for particular applications, it should beunderstood that the invention is not limited thereto. Those havingordinary skill in the art and access to the teachings provided hereinwill recognize additional modifications, applications, embodiments andsubstitution of equivalents falling within the scope of the invention.Accordingly, the invention is to be limited not by the specificdisclosure herein, but only by the appended claims.

What is claimed is:
 1. A surgical system, comprising: a fixation deviceincluding a first thread and a second thread, wherein the first threadand the second thread are opposing threads, and the first thread islonger than the second thread; and a hybrid drill/driver instrumentincluding: a pin extending between a driver end and a drill end, and ahandle movable between a first position in which it is secured to thedriver end of the pin and a second position in which it is secured tothe drill end of the pin, wherein the handle includes a cannulation forreceiving either the driver end or the drill end of the pin.
 2. Thesurgical system as recited in claim 1, wherein the driver end of the pinincludes an end geometry configured to engage a socket of the fixationdevice.
 3. The surgical system as recited in claim 2, wherein the endgeometry includes a hexagonal cross-sectional shape.
 4. The surgicalsystem as recited in claim 1, wherein the drill end of the pinterminates in a sharp tip.
 5. The surgical system as recited in claim 1,wherein the pin includes a diameter of about 1.0 mm to about 4.5 mm. 6.The surgical system as recited in claim 1, wherein the pin includes adiameter of about 1.5 mm to about 2.0 mm.
 7. The surgical system asrecited in claim 1, wherein the pin includes a plurality of markings foraccessing a depth of the pin in bone.
 8. The surgical system as recitedin claim 1, wherein the pin is solid and rigid.
 9. The bone fusionsystem as recited in claim 1, wherein the drill end of the pin includesa plurality of drill flutes or threads adapted to drill bone.
 10. Thesurgical system as recited in claim 1, wherein the first thread is aproximal thread and the second thread is a distal thread.
 11. Thesurgical system as recited in claim 1, wherein the second thread iswider than the first thread.
 12. A surgical system, comprising: afixation device including a first thread and a second thread, whereinthe first thread and the second thread are opposing threads, and thefirst thread is longer than the second thread; and a hybrid drill/driverinstrument including: a pin longitudinally extending between a driverend that includes an end geometry configured to engage the fixationdevice and a drill end that includes drilling threads and a sharp tip,wherein the pin is solid, and a handle removably securable to either thedriver end or the drill end of the pin, the handle including acannulation for receiving either the driver end or the drill end of thepin, wherein the handle is movable between a first position in which itis secured to the driver end of the pin and a second position in whichit is secured to the drill end of the pin.
 13. The surgical system asrecited in claim 12, wherein the first thread is a proximal thread andthe second thread is a distal thread.
 14. The surgical system as recitedin claim 12, wherein the second thread is wider than the first thread.15. A bone fusion system, comprising: a fixation device including asocket, a first thread, and a second thread, wherein the first thread islonger than the second thread; and a hybrid drill/driver instrumentincluding a pin longitudinally extending between a driver end adapted tomate with the socket of the fixation device and a drill end adapted todrill a bone hole for inserting the fixation device, wherein the firstthread and the second thread of the fixation device are opposingthreads.
 16. The bone fusion system as recited in claim 15, wherein thefixation device is a non-cannulated compression screw.
 17. The bonefusion system as recited in claim 15, wherein the first thread isseparated from the second thread along a shaft of the fixation device.18. The bone fusion system as recited in claim 15, wherein the drill endof the hybrid drill/driver instrument is provided with a plurality ofdrill flutes or threads.
 19. The bone fusion system as recited in claim15, wherein the first thread is a proximal thread and the second threadis a distal thread.
 20. The bone fusion system as recited in claim 15,wherein the second thread is wider than the first thread.